In bicycles having multi-speed transmissions, it is not possible to utilize a conventional bicycle brake and it is customary to utilize hand-operated brakes engaging the wheels or rims on the front and rear of the bicycles.
It has heretofore been suggested that brakes be incorporated in such bicycles which function upon rearward movement of the pedal cranks. For example, sprag or ratchet type brakes have been shown in U.S. Pat. Nos. 603,310, 868,671, 634,700, 670,473, 4,134,481, 3,486,586, and 3,888,334. Other similar constructions have been suggested in U.S. Pat. Nos. 3,831,716 and 3,858,689.
As far as the applicant is aware, none of these devices has proven satisfactory.
In U.S. Pat. No. 625,415, there is suggested a back pedaling brake which utilizes a ball moving along an incline in a disc rotatable with the pedal cranks to move a floating shoe into contact with the tire. One of the problems with such a device is that the attitude or orientation of the shoe is not controlled, it is very noisy and does not work smoothly or dependably.
Among the objectives of the present invention are to provide a bicycle brake for multi-speed bicycles which will operate quietly, positively and efficiently; which is extremely reliable; which will have long life and not be adversely affected by dirt and foreign material; and which utilizes a minimum number of parts.
In accordance with the invention, the bicycle brake comprises a disc rotatably mounted on the hub for rotation with the pedal cranks, a brake shoe pivoted to the frame and extending upwardly along the front of the rear tire of the bicycle and having a surface for engaging the tire upon actuation of the brake, a ball clutch arm pivoted on the shoe and extending upwardly and forwardly toward the periphery of the disc, and having opposed walls between which the periphery of the disc extends. The walls have inwardly facing grooves that taper transversely and longitudinally in a rearward direction, and a pair of balls is positioned in each groove between the disc and the respective wall. Means yieldingly urge the shoe away from the tire such that when the pedal cranks are pedaled rearwardly, the balls travel rearwardly along the grooves to pivot the ball clutch arm and, in turn, the brake shoe bringing the brake shoe surface into frictional contact with the surface of the rear tire.